ch.6 Flashcards
(30 cards)
What shape is the Earth?
The Earth is a huge, rocky sphere
What is the speed at which the Earth spins?
About 20 miles per second
What protects Earth’s surface from interplanetary space hazards?
Air and a magnetic field
What percentage of Earth’s surface rocks is made up of Oxygen?
45.5%
What is the density of water in g/cm^3?
1 g/cm^3
What is the average density of Earth?
5.5 g/cm^3
What are the two types of seismic waves?
P waves and S waves
What do P waves do?
They compress material and travel easily through solids and liquids
What do S waves do?
They move material perpendicular to the wave direction and only travel through solids
What is the composition of the Earth’s crust?
Solid, low density, made of silicates
What is the main component of the Earth’s inner core?
Iron and nickel
What is the estimated temperature of Earth’s core?
6500 K
What causes the high temperature in the Earth’s core?
Heat generated from impacts and radioactive decay
What is the outer core made of?
A mixture of iron, nickel, and sulfur
What is differentiation in Earth’s context?
The process where denser materials sink to the center and lighter materials rise to the surface
What keeps the Earth’s inner core solid despite high temperatures?
Tremendous pressure from overlying materials
What generates Earth’s magnetic field?
Currents in the liquid outer core
What is the primary function of Earth’s magnetic field?
To protect Earth from harmful solar particles
What is the composition of Earth’s atmosphere?
78% nitrogen, 21% oxygen, 1% other gases
What is the greenhouse effect?
It traps heat from infrared radiation, warming the Earth
What will the North Pole point to in about 14,000 years?
Vega
What is the process called when tectonic plates meet and one slips beneath another?
Subduction
How is the age of the Earth estimated?
Through radioactive decay, about 4.5 billion years
What type of seismic waves can travel through liquids?
P waves
